insoluble

adjective

in·​sol·​u·​ble (ˌ)in-ˈsäl-yə-bəl 

: not soluble: such as

a

: incapable of being dissolved in a liquid and especially water

also : soluble only with difficulty or to a slight degree

b

: having or admitting of no solution or explanation

an insoluble problem

c

archaic : indissoluble

insolubility

(ˌ)in-ˌsäl-yə-ˈbi-lə-tē 

noun

insoluble noun

insolubleness

(ˌ)in-ˈsäl-yə-bəl-nəs 

noun

insolubly

(ˌ)in-ˈsäl-yə-blē 

adverb

Synonyms

• impossible
• hopeless

Examples of insoluble in a Sentence

a substance insoluble in water

the seemingly insoluble mystery concerning the identity of the people who built these ancient structures

Recent Examples on the Web

There are two types of dietary fiber: soluble and insoluble, experts said. —Kristen Rogers, CNN Money, 26 July 2025

Oats are an abundant source of prebiotics and soluble and insoluble fibers, all of which support digestive health. —Amy Brownstein, Verywell Health, 23 July 2025

But what makes Tetris Attack superior is its two-player mode, where clearing your board drops massive payloads of insoluble junk on your rival. —Luke Winkie, Vulture, 18 June 2025

However, some may want to consume more insoluble fiber depending on their symptoms. —Akshay Syal, NBC news, 31 May 2025

Word History

Etymology

Middle English insolible, from Latin insolubilis, from in- + solvere to free, dissolve — more at solve

First Known Use

14th century, in the meaning defined above

Rhymes for insoluble

• soluble
• voluble
• indissoluble
• revoluble

Kids Definition

insoluble

adjective

in·​sol·​u·​ble (ˈ)in-ˈsäl-yə-bəl 

1

: impossible to solve

an insoluble problem

2

: impossible or difficult to dissolve

a substance insoluble in water

Medical Definition

insoluble

adjective

in·​sol·​u·​ble (ˈ)in-ˈsäl-yə-bəl 

: incapable of being dissolved in a liquid

also : soluble only with difficulty or to a slight degree